1. Field of the Invention
The present invention relates to a vehicular brake control apparatus exhibiting high braking force, and more particularly, to a brake control apparatus which can provide, to wheel cylinders, brake-fluid pressure higher than master-cylinder pressure generated by a master cylinder, when obtaining a higher braking force is desirable on a road having a high friction coefficient or the like.
2. Related Arts
U.S. Pat. No. 5,427,442 discloses a brake fluid pressure boosting apparatus for an automobile which boosts brake-fluid pressure applied to wheel cylinders to obtain an optimal braking force. In the brake fluid pressure boosting apparatus, a boosting effect by a brake-pressure booster is intensified in a state of panic braking wherein a driver hesitates to depress a brake pedal with maximum force. As a result, more than normal wheel-cylinder pressure is applied to the wheel cylinders in response to a driver's pedal-depression force, and high braking force is secured.
This apparatus, however, uses the same brake-pressure booster to boost brake fluid pressure under normal braking as well as to intensify the boosting effect in a panicky situation. As a result, there arises a possibility that if the brake-pressure booster fails, not only will not the boosting effect be intensified but the brake fluid pressure will not be boosted under normal braking.